Patent GB-790995-A (GB)
Title: Method for separating sulfonates from solutions containing them
Filed: 1954-05-27
Abstract: Metal organic sulphonates are recovered, in the form of complexes, from their solutions in petroleum distillates boiling in or above the kerosene range by reacting the sulphonate solution with a defined excess of a liquid aliphatic or cycloaliphtic polyhydroxy compound having a weight ratio of oxygen content to molecular weight of at least 0.3 whereby there is precipitated a complex of the sulphonate and polyhydroxy compound, the reaction taking place at a temperature below that which is unfavourable to the complex formation, preferably about 40 DEG  to 300 DEG  F., and in the absence of sufficient water to interfere with the formation of the complex, and separating the complex from the solvent.  The polyhydroxy compound is used in an amount which is greater than 1 gm. mol. per gm. atom of metal present, preferably 4-20 gm. mols., and is sufficient to cause precipitation of the complex.  The complex may be separated from the solvent by decantation or centrifuging, if desired after addition of a light solvent such as hexane, and then decomposed to give the free sulphonate and polyhydroxy compound by water-washing or by distilling off the polyhydroxy compound.  The method is utilizable in the recovery of mono- and polyvalent metal neutral and basic salts including salts of sulphonic acids derived from petroleum, wax, naphthenes, benzene, m-chlorbenzene, phenol, toluene and xylene. Numerous metal cations are mentioned.  The petroleum distillate may be kerosene, a gas-oil fraction or a lubricant distillate.  Solutions of petroleum sulphonates containing unwanted inorganic salts may first be purified by addition of an amount of an alcohol, glycol or glycol ether in sufficient amount to precipitate the sulphonates and then filtering.  In examples: (1) a mineral lubricating oil containing 3 per cent of calcium petroleum sulphonates is rapidly stirred with 2 per cent of ethylene glycol and then allowed to settle; an upper layer of oil free from sulphonate is removed and the lower layer, a reddish gum, is heated under nitrogen at 185-310 DEG C. to recover glycol leaving a calcium sulphonate residue; (2) similar calcium sulphonate solutions are each treated as in (1) to obtain sulphonate complexes with glycerol, ethylene glycol, propylene glycol, dipropylene glycol, a polypropylene glycol (M.W. 2000), butane-diols-2,3 and 1, 4 and hexane-2,5 diol and the sulphonate recoveries are compared with those obtained when n-butanol, pentaerythritol and diethylene glycol mono-n-butyl ether are used; (3) ethylene glycol is used as complexing agent in the removal of sodium, calcium or barium salts of mineral oil sulphonic acids, C9-alkylated naphthalene sulphonic acids and C9-12 alkylated benzene sulphonic acids, from their mineral lubricating oil solutions.  Other specified complex-forming polyhydric compounds are cyclopentane-1,2-diol, diethylene and triethylene glycols and high M.W. polyethylene glycols.ALSO:Mineral lubricating oil compositions comprise a neutral or basic mono- or poly-valent metal organic sulphonate obtained by reacting a solution of the metal sulphonate in a petroleum distillate boiling in or above the kerosene range with a defined excess of a liquid aliphatic or cycloaliphatic polyhydroxy compound having a weight ratio of oxygen content to molecular weight of at least 0.3 whereby there is precipitated a complex of the metal sulphonate and polyhydroxy compound, and separating and decomposing the complex (see Group IV (b)).  The sulphonic acids may be derived from wax, naphthenes, petroleum, benzene, toluene, chlorbenzene, pheno, xylene, C9-12 alkylated benzenes and C9 alkylated naphthalenes and numerous mono- and poly-valent metal cations are mentioned. Examples (1) and (3) describe the recovery of calcium petroleum sulphonates from a mineral lubricating oil solution using ethylene or propylene glycol as complexing agent, and their incorporation in a mineral lubricating oil to give a lubricant or a concentrate thereof.